Friday, January 9, 2015

SSD Controllers, Still Secret Sauce (Silicon Motion)

"SM2256 also features Silicon Motion’s proprietary
NANDXtend technology, which utilizes three levels of error correction and data
protection to effectively triple the program/erase cycle count for TLC
NAND. Combined with global
wear-leveling algorithms, the lifespan of an SSD utilizing the SM2256 is
significantly extended. It
also features real-time AES256 encryption, as well as being TCG Opal compliant."

"Controller is
a key edge in designing fast and low power flash memory systems.....even though by 2012 ....5 SSD
controller company acquired recently:

* In March of last year OCZ acquired
Indilinx * In may 2011 SanDisk bought Pliant*LSI
acquired SandForce in October * December brought Apple's acquisition of
Anobit * Now SK Hynix has acquired Link_A_Media"

We were privileged yesterday to meet with Robert Fan, Vice
President and General Manager of Silicon Motion to discuss their latest SSD
controller, the SM2256, which features support for TLC NAND. Historically, TLC NAND has had a reputation
of having low endurance and reliability, and hence was not suitable for use in
solid state storage devices.
Fast-forward to today, and we are seeing new technology and
software/firmware tools that are able to increase both the reliability and
endurance of TLC NAND, now making it a viable alternative to the more expensive
MLC NAND for use in certain SSDs.

The SM2256 supports a wide variety of NAND chips, including
ONFI 3.0, toggle 2.0 and asynchronous NAND.
It also supports the latest process geometries, including 1x, 1y, and 1z
NAND from all major NAND suppliers, and includes 3D NAND. The SM2256 is a 4-channel controller, yet
offers performance that rivals that of 8-channel controllers. It supports up to 32 NAND devices, which
gives it the capability to support up to 1TB of flash storage. The SM2256 also features a 16-bit wide DRAM
interface at DDR3/DDR3L speeds.

As an OEM solution, the SM2256 offers controller and
firmware from a single source, simplifying its usage. The firmware is both customizable and
upgradeable. The SM2256 supports both device sleep mode (DevSleep) and PHY
sleep mode (CFast PHYSLP), as well as TRIM functions. It also features S.M.A.R.T. drive performance
and health monitoring attributes.

In the above image, we see a trio of engineering samples that
are utilizing the Silicon Motion SM2256 with various NAND configurations. In
the close-up shot below, we see the SM2256 residing on the PCB of a 512GB SSD
utilizing 19nm TLC NAND and a 512MB DDR3 DRAM chip from Hynix.

The SM2256 also features Silicon Motion’s proprietary
NANDXtend technology, which utilizes three levels of error correction and data
protection to effectively triple the program/erase cycle count for TLC
NAND. Combined with global wear-leveling
algorithms, the lifespan of an SSD utilizing the SM2256 is significantly
extended. It also features real-time
AES256 encryption, as well as being TCG Opal compliant.

Performance of the SM2256 is augmented by utilizing an SLC
cache. Real world performance numbers
from qualifying OEMs put sequential read speeds at a range from 514MB/s to
545MB/s. Qualifying sequential writes
range from 458MB/s to 477MB/s. Random 4K
read speeds are averaging 97,000 IOPS, with random 4K write speeds averaging
around 40,000 IOPS. The screenshot below
shows similar results.

Silicon Motion has enjoyed widespread adoption of their
previous SM2246 controller, which is being utilized by over 30 OEMs as shown in
the graphic below. For additional information click on “SM2256″ in the
selection guide here at Silicon Motion’s website. This will take you to the product page for
the SM2256.

CES 2015 - Over the last year we've often discussed Silicon Motion's rise in the SSD controller space. The fabless semiconductor's SM2246EN controller was well received, first by smaller SSD manufacturers, and now by NAND flash fabs.

This week, SanDisk announced the new SSD Plus that is priced less than $70 in 128GB. The SSD Plus won't break any performance records but is clearly designed to break price barriers. SanDisk didn't brief media before introducing the SSD Plus at Storage Visions 2015, but since that time we've learned that Silicon Motion is inside with a custom variant of the SM2246EN controller.

Getting one NAND fab company to use your controller is a big step for a controller maker that was virtually unheard of one year ago. Getting two is big news for investors. Just days after the SanDisk announcement, Crucial, a division of Lexar and also a NAND flash manufacturer, announced the new BX100. Again, this new low cost consumer SSD with 16nm MLC flash is managed by a Silicon Motion SM2246EN controller.

They say when it comes it comes in threes. Analysts have recently come forward to state that Intel, a partner with Micron/Crucial/Lexar, has chosen a Silicon Motion controller for an unannounced consumer SSD that should break cover in the coming months. Most likely Intel will brand the new product in the 300 Series family, a low cost series that again is designed to increase the adoption rate of solid state storage technology, replacing mechanical hard drives.

None of this is all that radical when you know the history of the SSD market. SandForce quickly came to power but acquisitions and long product delays have left the door open for Silicon Motion to get a foot in the door. Now that Silicon Motion is sitting at the table, we think the real objective is for the company to use SM2246EN as a stepping stone for SM2256EN, a flash controller that takes advantage of new 3bit per cell technology that will further reduce the cost of solid state storage technology to consumers.